The goal of the Yale Interdisciplinary Immunology Training Program (YIITP) is to equip predoctoral and postdoctoral trainees with the intellectual and research foundations necessary to become independent scientists/educators investigating the immune system and its roles in human disease. The YIITP combines rigorous research training in a highly collaborative, interactive environment with a thorough academic program of instruction in immunology, microbiology, and related disciplines. The program offers training in virtually all aspects of molecular, cellular, and genetic immunology as well as host-pathogen interactions and a variety of autoimmune and inflammatory disorders. Areas of particular strength include innate immune recognition and function, B and T lymphocyte development, tolerance, and memory, antigen processing and presentation, signaling by adaptive and innate immune cells, the immune response to infectious organisms (including a number of Biodefense Priority Pathogens), vascular endothelial cells, and autoimmune diseases such as diabetes and systemic lupus erythematosus. As a group, the 35 YIITP trainers have an outstanding record of research accomplishment and training and many are national or international leaders in their fields. These faculty have primary appointments in 10 different Yale departments and currently have 69 predoctoral and 152 postdoctoral trainees working in their labs. Predoctoral training leading to the Ph.D. degree involves formal course work in Immunology and other areas of biology, research rotations, teaching, and the qualifying exam in the first two years, with dissertation research beginning late in year one and becoming the primary focus of activity after completion of the qualifying exam. Intensive training in the methods, logic, and responsible conduct of research are supplemented with a wide array of opportunities for scientific interactions. The average time to obtain the Ph.D. degree is 5.5 years. Postdoctoral training focuses intensively on research in the laboratory of one or more of the trainers and is enriched by many opportunities for collaboration and interaction. The vast majority of YIITP trainees go on obtain independent research and teaching positions at academic institutions or research positions in biotechnology companies. Extensive efforts are made by YIITP trainers and Yale Graduate and Medical Schools to attract and retain trainees from diverse backgrounds, particularly underrepresented minority groups. This application requests funding to support 12 predoctoral and 3 postdoctoral trainees at any one time;they are supported by this grant for a maximum of 3 and 2 years, respectively. Relevance: This program trains scientists to pursue research careers focused on investigating the immune system, the system of the body responsible for combating infectious diseases. Such research is expected to yield new vaccines, new therapies to combat viruses and bacteria, and new treatments for autoimmune diseases such as diabetes, lupus, and rheumatoid arthritis and hypersensitivity disorders such as asthma.